1. Technical Field
The present invention relates to people moving devices in general, and to treadplates for people moving devices in particular.
2. Background Art
Escalators, moving walkways, and other people moving devices efficiently move a large volume of pedestrian traffic from one point to another. Passengers step on moving treadplates (or belts, or pallets, or steps, etc.) and are transported along at a constant rate of speed.
The treadplates are attached to a step chain which travels in a closed loop from a first landing of the people moving device to a second landing and back. Specifically, the treadplates exit the first landing and travel exposed from the first landing to the second landing. From there, the steps reverse direction within the second landing and return to the first landing concealed within the frame of the device. Finally, the steps reverse direction within the first landing, thereby completing the loop.
A person of ordinary skill in the art will recognize that safety is a significant concern in the entry and exit points of a people moving device. Passengers go from stepping on a surface at a zero velocity to stepping on a surface at a constant velocity greater than zero. As a result, there is an opportunity for a passenger to lose his or her balance.
Numerous solutions have been offered to address these safety concerns. In some cases, for example, caution signs are deployed near the entry and exit points. These signs must be positioned out of the moving path, however, or they too become a safety hazard. Positioning the signs out of the moving path decreases the effectiveness of the warning and detracts aesthetically. In other cases, cautionary colors are painted on either the treadplates or the landing entry (typically called the combplate) to highlight the difference in velocity between the parts. The difficulty with a painted coating is that the paint wears off relatively quickly, and therefore increases maintenance costs as well as creates an aesthetic blemish. In still other instances, the treadplates are machined to accept cautionary colored plastic inserts which are typically riveted to the step. A disadvantage of this approach is that the machining process significantly increases the cost of the treadplates. In addition, if the insert works free from the treadplate, the now loose insert and the machined treadplate become a safety hazard. Another disadvantage of machining the step is that the plastic insert cannot be attached to the forward edge of the treadplate. The machining step necessary to make room for the insert would require more stock than is normally cast in the treadplate.
In short, what is needed is a durable means for alerting passengers of the difference in surface velocity at the entry and exit points of a people moving device, which is easily recognizable.